140.L-乳酸メチルを用いた光学活性メタクリル酸エステルの合成

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The purpose of this study is the synthesis of new polymers by using reagents made from natural products. This paper describes the synthesis of a monomer from L-methyl lactate (L-MLA), which is commercially available, and methacrylic acid (MA) or its derivative. At first, the condensation reaction of L-MLA and MA with dicyclohexylcarbodiimide (DCC)(solvent: tetrahydrofuran (THF); room temperarure) was carried out in order to synthsize an optically active methacrylate, L-methyl lactate methacrylate (L-MLAM). The structure of L-MLAM obtained by this reaction was confirmed by IR and ^1H-NMR spectroscopy. The yield of L-MLAM was low (30%), however, because a N-acylurea was also formed in the reaction. This N-acylurea might be formed by the condensation of MA and dicyclohexylurea (DCC was converted into dicyclohexylurea in the reaction). The formation of the N-acylurea can be explained by the lower reactivity of the OH group of L-MLA than that of the NH group of dicyclohexylurea. The reaction of L-MLA and methacryloyl chloride (MC1) in the presence of pyridine in THF also gave L-MLAM, but in a somewhat higher yield (46%). The reaction system was heterogeneous because of the low solubility of the complex of pyridine and MC1 in THF, and the reaction rate was quite low. The yield may be improved under homogeneous-reaction conditions. There is thus some room for improvement in this method.
2000-03-10